Direct-acting, magnetically-actuated fluid control valves are used in a variety of applications within industry. Typically, such valves include a solenoid coil and a metallic armature body manufactured from a ferromagnetic alloy. The metallic armature body is capped with an elastomeric sealing member which seals against a seat within the body of the valve to control the flow of fluid through the valve. A spring may bias the metallic armature body into a normally open or normally closed position, whereupon powering the solenoid coil of the valve magnetically actuates the metallic armature body against the bias (either toward the seat to seal a fluid port or away from the seat to unseal a fluid port, respectively) to alter the closure state of the valve. The elastomeric sealing member may provide for both fluid sealing and impact absorption during operation of the valve.
Self-actuating fluid check valves are also commonly used within industry, household fixtures, and consumer products. Typically, such valves include a resilient sealing member, such as an elastomeric ball or disc, which may be biased against a seat in the valve body by gravity, by preloading via a spring, or by the intrinsic resilience of the sealing member (such as in an umbrella valve). The flow of fluid from an upstream side of the valve displaces the sealing member from the seat, allowing fluid to flow past the sealing member and to a downstream fluid port in the valve. The biasing of the sealing member, as well as any flow of fluid into the downstream port the valve (a reversed flow), drives the sealing member toward seat and, upon sealing engagement, serves to prevent fluid from flowing past the sealing member to an upstream fluid port of the valve. Fluid check valves may also desirably have a minimum “cracking pressure,” defined as the minimum upstream pressure required to open the valve and start fluid flow through the valve. That cracking pressure is conventionally varied by altering the preloading displacement or spring constant of a biasing spring, by altering the preloading displacement or modulus of elasticity of the sealing member material, or by related means.